Your question did not include the title of the work you are studying, but I am assuming that it refers to Shakespeare's Macbeth because of the word "murder" and the reference to Act 2, Scene 4. This short scene seems to have been written mainly to convey information to the audience in the conversation between Ross and Macduff.

Before Macduff enters, Ross and an Old Man are talking about weird things that have been happening since Duncan's murder. The sky is dark in the middle of the day. A falcon was seen being killed by a little owl. Duncan's horses turned wild, broke out of their stalls, and tried to eat each other. All of this foreshadows more and more troubles for Scotland under the illegitimate rulership of an assassin. It is significant that none of the characters, including Macduff, dares to speak of the suspicions all of them are harboring. Macbeth will rule by terror.

When Macduff enters, he tells Ross some essential facts. It has been assumed that Malcolm and Donalbain were responsible for their father's murder. Macbeth is to be made king.

He is already named and gone to Scone

To be invested.

Significantly, Macduff tells Ross that he will not attend the ceremony at Scone. Macbeth will regard this as an insult and it will lead to tragic consequences for Macduff.

The dialogue between Ross and the Old Man is not really necessary. It must have been inserted to make this short scene a bit longer and to prevent it from being too obviously intended to convey information via Macduff and Ross. Shakespeare frequently used such conversations between two characters for purposes of exposition. Another good example is in Act 4, Scene 4 of Hamlet, in which Hamlet questions a Captain about the presence of Fortinbras and Soldiers, beginning with: